Ghost of a chance: Gregg v. Scott in the House of Lords.

• Author: Black, Vaughan
• Position: United Kingdom, Canada

In January 2005 the House of Lords released its long-awaited decision in Gregg v. Scott. (1) By a 3:2 margin the court held that factual causation in medical malpractice cases should not be resolved on a loss-of-chance basis. This note presents an account of the reasons in Gregg v. Scott. It goes on to offer some criticism of those reasons and an assessment of the implications of the decision for the law of Canada.

1. Loss-of-chance causation and the facts in Gregg v. Scott

   Loss-of-chance functions as an exception to the general rule for factual causation in tort. That general rule for cause-in-fact requires a plaintiff to prove on the balance of probabilities that were it not for the defendant's fault, the plaintiff would not have suffered the harm in respect of which she is claiming. Under that orthodox balance-of-probabilities standard, a plaintiff loses unless she can show that in the absence of the defendant's error, her injury would most likely not have occurred.

   Loss-of-chance causation permits a plaintiff who cannot satisfy the traditional balance-of-probability standard to nevertheless succeed, at least in part. It does so by permitting such a plaintiff to claim that the defendant's fault deprived her of some chance of not suffering the harm in question. There is an alternative way of describing loss-of-chance causation. Under this description, loss-of-chance causation preserves the balance-of-probability standard but permits the plaintiff to "re-describe" the harm, so that instead of claiming to have suffered harm X--where X is, say, a broken leg--the plaintiff claims to have been deprived of some chance of not being subjected to harm X.

   It is an interesting point whether these alternatives are just two different ways of describing the same thing, or whether they are in fact different things, but in terms of the award the plaintiff receives they are extensionally equivalent. That is, under either approach the plaintiff is then awarded damages calculated by taking the dollar value which would be awarded in respect of the root harm, and discounting that by the probability that the harm would have happened in any event.

   An illustration would likely assist. I offer one from an area where loss-of-chance causation has been successfully invoked, first in England and later in Canada. (2) A plaintiff might claim that her lawyer carelessly failed to launch a civil action on her behalf before the applicable limitation period expired. Since the original claim is now barred, such a plaintiff would seek damages from her careless lawyer based on the total amount she would get had she won the suit that the lawyer should have launched. However, the defendant lawyer might reply that, even had he commenced the suit in time, the claim was a weak one with, say, only a 30% chance of success. The lawyer would then go on to argue that, according to the balance-of-probabilities standard, the plaintiff has failed to prove that she lost anything, since more likely than not the plaintiff would have failed in the originally-contemplated suit. Loss-of-chance causation permits a plaintiff in that position to succeed and get damages amounting to 30% of the sum that she would have been awarded had she won the original suit.

   But there is a catch. Loss-of-chance causation is not generally available. It has been applied in only a small number of areas. It operates in the example just described, and in some other pockets of the law, (3) but courts have not adopted it as a generally applicable causal standard. In most types of claims, courts have proven unreceptive to defendants' attempts to characterize their cases as claims for a reduced chance of not suffering a given harm.

   In its 1987 decision in Hotson v. East Berkshire Area Health Authority (4) the House of Lords overruled a decision to apply loss-of-chance causation in a medical malpractice case. Relying in part on Hotson, in its 1991 decision in Laferriere v. Lawson (5) the Supreme Court of Canada overruled a Quebec Court of Appeal decision which had used a loss-of-chance approach in a claim for delictual responsibility in a clinical context. While there may at one time have been a measure of doubt as to whether that case represented the law in Canada's common law jurisdictions, in 2003 the Ontario Court of Appeal put an end to uncertainty on that point. It ruled that Laferriere stood for the proposition that loss-of-chance causation was not available in medical malpractice cases in Canada. (6)

   The boundaries of loss-of-chance remain uncertain. The reported decisions in which it has been applied are a motley group, with no obvious common feature to set them apart from cases where courts have refused to employ a loss-of-chance approach to factual causation. Moreover, there is no consensus in academic writing as to where loss-of-chance causation might legitimately be invoked. Arguments can be advanced for never resorting to loss of chance, or for making it available in every case (though this would amount to a striking transformation of civil litigation), or for applying it only in some sub-set of disputes--for instance in contract but not tort, or in cases where proof of loss depends on the hypothetical act of some third party, or only in cases where the chain of events that must be hypothesized in order to conduct the causal inquiry can be said to be completely determined by the incidents which have taken place. (7)

   Against this background of judicial randomness and scholarly dissension it is unsurprising that some plaintiff might attempt to persuade courts to revisit the question of whether loss of chance might be available in case of medical malpractice, or at least in some sub-set of such cases. That brings us to Gregg v. Scott.

   Mr. Gregg presented to Dr Scott with a lump under his left arm. Scott diagnosed the lump as innocuous and recommended neither treatment nor further investigation. Nine months later Gregg was seen by another physician who correctly diagnosed the lump as cancerous. During the period of delay the lump had grown in size and the cancer had spread. Gregg sued Scott for negligence and the trial judge found that Scott's performance fell below the applicable standard of care. Next, based on expert evidence, the judge found that the delay due to Scott's carelessness had reduced Gregg's prospects of survival from 42% to 25%.

   On those findings the judge dismissed the plaintiff's claim since, on the balance of probabilities, the delay had not harmed him. That is, had Scott correctly diagnosed and properly treated Gregg, Gregg never had a better than even chance of beating the cancer so, more likely than not, Scott's fault had caused Gregg no loss. Scott's argument that he should be awarded damages to compensate him for the reduction of his chance of being a survivor was rejected on the basis that Hotson stood as a bar to loss-of-chance claims in medical malpractice cases. Gregg appealed but the Court of Appeal agreed with the trial judge. (8) Gregg then appealed to the House of Lords.

2. Gregg v. Scott in the House of Lords

   In the House of Lords all five judges acknowledged that loss-of-chance causation operated in some areas of English law but had not yet been applied in a medical malpractice case. The issue was thus whether that approach to causation should be introduced to the health care area. As Lord Phillips put it,

    This appeal has raised an important issue of policy. Should this House introduce into the law of clinical negligence the right of a patient who has suffered an adverse event to recover damages for the loss of a more favourable outcome? (9) 

   I begin with the reasons of the two dissenting law lords, since the reasons of the three in the majority are most easily understood as responses to the dissents. Borrowing a page from Lord Denning's book by starting his speech with a string of plain, short sentences, Lord Nicholls began with a forceful account of the deficiency of the existing law.

    A patient is suffering from cancer. His prospects are uncertain. He has a 45% chance of recovery. Unfortunately his doctor Negligently misdiagnoses his condition as benign. So the necessary treatment is delayed for months. As a result the patient's prospects of recovery become nil or almost nil. Has the patient a claim for damages against the doctor? No, the House was told. The patient could recover damages if his initial prospects of recovery had been more than 50%. But because they were less than 50% he can recover nothing.

   This surely cannot be the state of the law today. It would be

   irrational and indefensible. The loss of a 45% prospect of

   recovery is just as much a real loss for a patient as the loss of a 55% prospect of recovery.... [Application of the traditional standard] would make no...